Compact Dual-frequency Research Articles

Compact Dual-Frequency Slot Antenna for C-Band Applications Based on Substrate Integrate Waveguide

Compact Dual-Frequency Slot Antenna for C-Band Applications Based on Substrate Integrate Waveguide

Experiments of Microwave Ablation Based on Dual-Frequency Antenna Under Pulsed Mode

In this letter, we review the microwave ablation (MWA) under pulsed wave (PW) mode and perform the experiments by using a dual-frequency antenna. Parameters such as frequency (915 MHz or 2450 MHz), excitation power (40 W or 60 W), duty cycle (40%–60%), cycle (10 ms–100 s), and durations (5 min or 10) min are variably combined in different experimental schemes for investigation. Based on the results of these experiments, which use our super compact dual-frequency antenna and egg white as a reference tissue environment, it can be seen that PW MWA may reduce backward heating and increase ablation roundness to 0.964 (compared to a traditional continuous wave (CW) ablation roundness of 0.5). For further verification of these results and for comparison, a single-frequency antenna is also used under PW mode and the achieved ablation roundness is 0.91, which is also greater than that of 0.55 under CW mode. PW MWA can thus be considered as an effective candidate for tissue ablation during the treatment of tumors.

Semi-Supervised Classification of Dual-Frequency PolSAR Image Using Joint Feature Learning and Cross Label-Information Network

Dual-frequency polarimetric synthetic aperture radar (PolSAR) data can provide more information than single-frequency data, which can effectively improve classification accuracy. However, how to obtain sufficient and non-redundant feature representation from dual-frequency PolSAR data remains to be resolved. Besides, deep learning has shown good performance in PolSAR image classification, but it often requires a large number of labeled samples to participate in the training process, which is time-consuming and labor-intensive. In this paper, we propose a novel dual-frequency PolSAR image semi-supervised classification method that combines a dual-frequency joint feature learning (DFJFL) module with a cross label-information network (CLIN). First, the DFJFL module is developed based on the consistency and complementarity of dual-frequency data. It eliminates information redundancy by feature constraint loss function, and obtains compact dual-frequency joint feature representation. Subsequently, in order to avoid the influence of speckle noise, the proposed CLIN not only applies consistency regularization under network perturbation, but also uses the scattering mechanism of PolSAR data to find similar sample pairs to complete the consistency regularization under input perturbation, thereby achieving semi-supervised classification for PolSAR data. Experiments on four real dual-frequency PolSAR datasets verify that the proposed method can effectively extract dual-frequency PolSAR information, and make full use of unlabeled samples to improve classification accuracy. At the same time, compared with several related image classification algorithms, the proposed method could achieve the best performance.

Design and experimental verification of compact dual-band SIW power dividers with arbitrary power division

Abstract This paper communicates the design and experimental validation of dual-band SIW power dividers (single-stage and double-stage) with arbitrary power division. The dual-band power dividers are developed for WiMAX (3.5 GHz) and WLAN (5 GHz) applications. The proposed SIW power dividers are realized by a rectangular cavity, two rows of metallic-vias and one pair of unequal complementary split-ring resonators (CSRRs). Two resonating frequencies are produced below the waveguide cut-off frequency due to the unequal CSRRs etched-out on the top-surface of the cavity, which results in size reduction. To realize arbitrary power division, two output-ports are configured asymmetric with respect to input-port. The power division is varied by altering the distance between the two output-ports. Finally, two compact dual-frequency power dividers (single-stage and double-stage) working at 3.5 and 5 GHz are designed and validated through fabrication and measurement. The fabricated prototype exhibits dual-band operation, compact size (0.027 λ g 2 ${\lambda }_{g}^{2}$ ), good magnitude imbalance, return loss and isolation.

A Compact Dual Notch Frequency Reconfigurable Antenna for WIMAX,DSRC, RADAR and Ku band Communication Applications

A frequency reconfigurable ultra-wide band antenna with dual notch bands is proposed in this paper. PIN diodes are located on ultra-wide band monopole antenna and are investigated for frequency reconfigurable characteristic of the proposed antenna. Multi-bands and narrow bands have been achieved by different combinations. Proposed antenna is fabricated on FR-4 substrate of dimensions 37 x 40 x 0.8mm3. For the successful combinations, antenna performance parameters like S11 characteristics, surface current distribution, peak gain, radiation efficiency and 2D radiation patterns are analyzed and illustrated in the paper. Peak gain of 4.83dB is obtained in operating band for D1, D2= 0, 1 combination. Radiation efficiency is not less than 70% in the entire operating bands. Results are analyzed experimentally for validating proposed antenna. Simulation based results and measured results are in good agreement.

Compact Dual-Frequency Antenna Array With Large Frequency Ratio

A dual-fed dual-frequency shared-aperture antenna array with a large frequency ratio is investigated. Its unit cell consists of a microwave ground-surrounded patch antenna and a millimeter-wave substrate-integrated 2×2 slot antenna subarray. The former is excited in the fundamental TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode, whereas the slot elements are excited in their fundamental mode. Based on the dual-frequency antenna unit, a dual-frequency antenna array is designed. To demonstrate the idea, a prototype that consists of a C-band 2×2 patch antenna array and a Ka-band 8×8 slot antenna array was designed, fabricated, and tested. Its matching and radiation characteristics are studied for both bands. Reasonable agreement between the measured and simulated results is observed. Excellent measured intraband isolations of over 32 dB are obtained.

Compact Dual-Frequency Relativistic Magnetron With TEM Mode Output

We propose a compact dual-frequency relativistic magnetron with TEM mode output. The resonant system consists of two axially separated beam–wave interaction regions for generating dual-frequency microwave. Under the same diode voltage and axial magnetic field, the RF field of the operating $\pi $ -mode can almost be simultaneously established. Furthermore, the diffraction output and the all cavity axial extraction are integrated to realize the TEM mode output. Particle-in-cell simulation shows that when the diode voltage is 400 kV, microwaves with output powers of 740 and 876 MW generate, with frequencies of 2.05 and 2.35 GHz, respectively. With an axial magnetic field of 0.44 T, the device efficiency of over 43% in the dual-frequency relativistic magnetron is achieved.

A Novel Dual-Band (38/60 GHz) Patch Antenna for 5G Mobile Handsets.

A compact dual-frequency () microstrip patch antenna with novel design is proposed for 5G mobile handsets to combine complicated radiation mechanisms for dual-band operation. The proposed antenna is composed of two electromagnetically coupled patches. The first patch is directly fed by a microstrip line and is mainly responsible for radiation in the lower band (). The second patch is fed through both capacitive and inductive coupling to the first patch and is mainly responsible for radiation in the upper frequency band (). Numerical and experimental results show good performance regarding return loss, bandwidth, radiation patterns, radiation efficiency, and gain. The impedance matching bandwidths achieved in the and bands are about and , respectively. The minimum value of the return loss is dB for the band and for the band. Radiation patterns are omnidirectional with a balloon-like shape for both bands, which makes the proposed single antenna an excellent candidate for a multiple-input multiple-output (MIMO) system constructed from a number of properly allocated elements for 5G mobile communications with excellent diversity schemes. Numerical comparisons show that the proposed antenna is superior to other published designs.

Compact Wideband Dual-Frequency Antenna Based on a Simplified Composite Right/Left-Handed Transmission Line with Hilbert Curve Loading

This paper addresses the issues of low bandwidth, gain, and efficiency of miniaturized microwave antennas by proposing a novel wideband dual-frequency coplanar waveguide antenna design based on a simplified composite right/left-handed (SCRLH) transmission line structure with Hilbert curve loading. The multifrequency characteristics of the SCRLH transmission line structure are evaluated theoretically, and the antenna parameters promoting bandwidth broadening under zeroth-order resonance (ZOR) and first-order resonance (FOR) mode operation are evaluated. The bandwidth broadening in the ZOR and FOR modes is accordingly revealed to be independent of the antenna length, and the structure therefore facilitates wideband operation under miniaturization. Finally, the dual-frequency ZOR and FOR mode antenna design with center frequencies of f0 = 1.865 GHz and f1 = 2.835 GHz is validated via simulation, and the performance of a compact prototype antenna is evaluated experimentally. The −10 dB return loss bandwidths at f0 and f1 are 187 MHz (from 1.773 GHz to 1.96 GHz) and 368 MHz (from 3.002 GHz to 3.37 GHz), and the corresponding relative bandwidths are 10.1% and 11.5%, respectively. The experimentally measured peak gains and radiation efficiencies at f0 are 1.54 dB and 81.3%, respectively, and those at f1 are 1.71 dB and 74.2%, respectively.

Magnetic Frequency Tuning of a Multimodal Vibration Energy Harvester.

In this paper, we present a novel vibration-based piezoelectric energy harvester, capable of collecting power at multiple operating frequencies and autonomously adapting itself to the dominant ambient frequencies. It consists of a compact dual-frequency resonator designed such that the first two fundamental natural frequencies are in the range of [50, 100] Hz, which is a typical frequency range for ambient vibrations in industrial environments. A magnetic frequency-tuning scheme is incorporated into the structure, which enables the frequency agility of the system. In contrast to single frequency harvesters, the presented approach combines multi-resonance and frequency tunability of both modes enabling a larger operative bandwidth. We experimentally demonstrate independent bi-directional tunability of our dual-frequency design. Furthermore, a control algorithm based on maximum amplitude tracking has been implemented for self-adaption of the system. The latter has been demonstrated in a system-level simulation model, which integrates the dual-frequency resonator, the magnetic tuning, and the control algorithm.

Wideband Dual-Frequency Antenna With Large Frequency Ratio

This communication investigates a new type of compact dual-frequency antenna, which is realized by using a single rectangular dielectric block with a groove along its center. It integrates a microwave dielectric resonator antenna (DRA) with a millimeter-wave Fabry–Perot resonator antenna (FPRA). The DRA is fabricated out of a dielectric block, excited by a vertical conducting strip on its side wall. The FPRA is realized by sticking the adhesive copper tape on the surfaces of the groove, forming a pair of parallel plates and the ground plane. The FPRA is excited by a sleeve-integrated L-probe, which suppresses the cross-polar fields and widens the bandwidth of the FPRA. To validate the idea, a dual-frequency antenna, covering both the 2.4 and 24 GHz ISM bands, was designed and measured. The DRA operates in its TEx111 mode, whereas the FPRA operates in its fundamental mode. Next, a wideband dual-frequency antenna was designed to further cover the 4G and future 5G frequency bands. Both of the TEx111 and TEx113 modes of the DRA are excited, broadening the bandwidth in the microwave band. Also, the FPRA mode and two L-probe modes are simultaneously excited to increase the bandwidth in the millimeter-waveband. The S-parameters, radiation patterns, antenna gains, and antenna efficiencies of the dual-frequency antennas are studied in detail. Reasonable agreement between the measured and simulated results is observed.

A Compact Triangular Ring Patch Antenna For Radio Location And Fixed Satellite Applications

A compact dual frequency triangular ring patch antenna has been designed for the radiolocation and fixed satellite applications in the X and Ku bands with an operating frequency of 8.55GHz and 19.44GHz. The patch has been considered as triangular ring to get the necessary frequency of operation. Flame Retardant Glass epoxy is taken as substrate material which are having a thickness of 2mm and a 50Ω microstrip line has been used to excite the antenna. Slotted patch technique has been implemented to attain the dual frequency of operation. Proposed antenna work as two radiators of which one is outer perimeter of patch and the other is the inner perimeter. The overall dimension of the antenna is 14.3mm×14.3mm×2mm which is 0.61λ×0.61λ making the proposed antenna a compact one. The Proposed antenna is having dual frequency of operation at the frequencies of 8.55GHz and 19.44GHz with again of 6.06dB and 5.82dB respectively. Commercially available 3D simulator Ansys HFSS software has been used to design the proposed antenna.

A compact dual frequency microstrip antenna

In this study, we present a new technique for the development of a dual frequency microstrip antenna. Two identical polarizations at two far apart frequencies have been generated in a compact configuration which uses two elements fed by a single feed line. This design technique provides an independent control to the desired frequencies and reduces element size by 50% compared to the conventional design at the cost of a marginal decrease in gain. The proposed antenna produces dual resonances at 4.056 and 4.96 GHz. It yields impedance bandwidths of about 1.71% at the lower resonance and 1.41% at the higher resonance respectively. It exhibits 7.0 and 6.6 dBi gains at the lower and upper resonances respectively which are 0.3 and 0.7 dB lower than a conventional patch. The measured cross polar discriminations of the proposed antenna are also comparable to the conventional patch. The measured efficiencies are 81.3% and 78.1% respectively.

A compact dual frequency double U-slot rectangular microstrip patch antenna for WiFi/WiMAX

This letter presents design of a compact (0.32λg × 0.15λg) dual frequency rectangular microstrip patch antenna for wireless applications. Dual frequency operation is achieved by inserting a pair of symmetric face-to-face U-slots, which results in excitation of and modes, on a narrow radiating patch upon appropriate offset coaxial feeding. In addition to compactness, the embedded slots provide two degrees of freedom for tuning the resonant frequencies independently. A physics based approach is adopted in deriving empirical expressions for lower and upper resonant frequencies by analysing the surface current distribution on the patch. Parametric studies of the slots' dimensions show that it can cover the frequency ranges from 1.72 to 4.1 GHz without giving rise to any grating lobes. This antenna geometry can be used for various standards like GSM (1800–1900 MHz), DCS (1710–1880 MHz), PCS (1880–1990 MHz), UMTS (1920–2170 MHz), LTE2300 (2300–2400 MHz), WiFi (2400–2480 MHz), WiMAX (3467–3521 MHz), etc. by appropriately choosing slot parameters. Many typical designs of the proposed antenna geometry are possible with different slot dimensions according to the requirement of these bands. One such design which supports WiFi and WiMAX has been fabricated on FR4 substrate. The measured results for this antenna are also included here.

Compact dual-frequency fiber laser accelerometer with sub-μg resolution

We demonstrate a compact and high-resolution dual-polarization fiber laser accelerometer. A spring-mass like scheme is constructed by fixing a 10-gram proof mass on the laser cavity to transduce applied vibration into beat-frequency change. The loading is located at the intensity maximum of intracavity light to maximize the optical response. The detection limit reaches 107 ng/Hz1/2 at 200 Hz. The working bandwidth ranges from 60 Hz to 600 Hz.

Dual-Frequency Folded-Parallel-Plate Antenna With Large Frequency Ratio

This communication investigates a new compact dual-frequency antenna with a large frequency ratio, which consists of a pair of folded parallel plates. It integrates the microwave parallel-plate waveguide resonator antenna (WRA) with the millimeter-wave Fabry-Perot resonator antenna (FPRA), with their resonant frequencies independent of each other. Due to the folded structure, the profile of the proposed antenna is lower than that of the conventional parallel-plate WRA. The WRA part is excited by a hook-shaped strip on its top, whereas the FPRA is excited by an L-probe with a half-ring sleeve. To demonstrate the idea, a dual-frequency antenna that covers the 2.4- and 24-GHz ISM bands was designed. ANSYS HFSS was used to simulate the S-parameters, radiation pattern, and antenna gain and reasonable agreement between the measured and simulated results is obtained.

Design of compact dual-frequency antenna with bandwidth enhancement

A compact dual-frequency antenna with enhanced bandwidth is proposed in this paper. Dual-frequency operation is realized by cutting a slot in the elliptical patch, and bandwidth enhancement is achieved by using a partial ground plane. Compared with the conventional half-wave antenna, the antenna has a compact size of 24 × 20 mm2, which equals to 0.38 λ1× 0.31 λ1(λ1, the guided wavelength at the first resonant frequency). The dual-frequency antenna with a partial rectangle ground and a partial arc-shaped ground is investigated for impedance matching. Simulated results indicate that the antenna with a partial arc-shaped ground can obtain a larger bandwidth for two bands than that with a partial rectangle ground. Experimental results show that the antenna with a partial arc-shaped ground can operate in 2.4 and 5 GHz bands, which covers the 2.4, 5.2 and 5.8 GHz for wireless local area network. The impedance bandwidths of two bands are 9.5 and 13.6%, respectively. Also, good radiation performances have been achieved at two bands.

Compact Differential Dual-Frequency Antenna Based on Metamaterial

In this paper, a compact differential dual-frequency antenna based on metamaterial is presented. To realize the dual-frequency operation of the left-handed and zeroth-order resonant modes, a ring slot and two diagonal slots are embedded in the radiating patch, and via holes are employed to connect the patch and the ground plane. In order to improve the impedance matching of the antenna, four corners are truncated in the ground plane. The proposed antenna has a compact size of 40 mm × 40 mm, which equals to 0.25 λ1 × 0.25 λ1 (λ1, the guided wavelength at f1). The simulated results show that the proposed antenna can operate at 0.89 and 1.79 GHz bands. Meanwhile, good radiation performances are achieved.

Terahertz intracavity generation from output coupler consisting of stacked GaP plates

We demonstrate intracavity terahertz generation from an output coupler of a compact dual-frequency solid state laser. The output coupler consisting of unbonded and stacked GaP plates is used as a second-order nonlinear medium where the difference-frequency generation takes place. When quasi-phase matching is achieved within the alternatively rotated GaP plates, terahertz output power is significantly enhanced compared with that for the corresponding external-cavity configuration.

A novel compact dual-frequency monopole antenna for quad-band mobile terminal application

A novel compact dual-frequency monopole antenna with a parasitic radiating strip is presented. The antenna with a height of only 6.5 mm, printed on the upper board and side board, is vertically placed at the upper-left corner of the main board to reduce the occupied area of the main board. A parasitic strip with meandered structure is added into the antenna, and hence, the dual-frequency characteristic is achieved to broaden the bandwidth. The measured −10 dB impedance bandwidth is 960 MHz (1920–2880 MHz), covering the UMTS (1920–2170 MHz), WiBro (2300–2400 MHz), WLAN (2400–2483 MHz), and WiMAX (2500–2690 MHz) bands. Thus, the proposed antenna is suitable for multisystem mobile terminal applications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1743–1746, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26876